This is not true anymore. The majority of people in the Western world play computer games. It's just that they are now much older than we were "back in the day" - the average age of a gamer now is 36 and climbing. And they are much, much, MUCH more casual on the average. Not even "Hello Kitty Island Adventure" casual, more like "Words with friends" casual.
So companies are going after people like that. "Your mom" - literally.
The combined total of all subscribers of all MMO's in the Western world is miniscule. It's less, much less, than 1% of the population.